Untersuchung der Hochtemperaturverzunderung/-entkohlung eines Kugellagerstahls (100Cr6) in unterschiedlichen Verbrennungsatmosphären (Erdgas- und Wasserstoffverbrennungsatmosphäre)

In this study, the high-temperature oxidation of a 100Cr6 bearing steel was investigated under two different combustion atmospheres: a conventional natural gas combustion atmosphere and a hydrogen combustion atmosphere. The experiments were carried out isothermally at six temperature levels (800 °C, 900 °C, 1000 °C, 1100 °C, 1200 °C, and 1250 °C), with each experiment lasting 120 minutes. The literature review focused on the fundamental principles of high-temperature oxidation of bearing steels as well as chromium- and silicon-containing steels in different atmospheres. In the experimental part, simultaneous thermal analysis (STA) was used to measure the change in mass during various time¿temperature¿atmosphere programs. The STA measurements and metallographic examinations showed that, in the hydrogen combustion atmosphere, a stronger oxide formation of approximately 35 wt% occurs at temperatures above 1100 °C. The influence of temperature is also significant: the higher the temperature, the more pronounced the oxidation. This is due to the fact that elevated temperatures promote diffusion processes and mass transport at the metal¿oxide interface With regard to decarburization, no differences were found between the two combustion atmospheres. The reason for this is that the oxide layer consists mainly of FeO (wüstite), and the pO2 partial pressure at the oxidation interface is similar in both combustion atmospheres, so no differences in the decarburization reactions were observed. Finally, based on the determined oxidation parameters, a model was developed to calculate the scale growth of the 100Cr6 alloy in the temperature range of 800 °C to 1250 °C for up to 2 hours in both combustion atmospheres.